Almost 29,000 people across the Illawarra Shoalhaven Local Health District came forward for testing in the two weeks before new cases in Wollongong were reported, NSW government data shows.
The figures for the 14 days to Monday, July 19 show that testing numbers peaked last Wednesday, July 14, when almost 3200 people came forward for testing.
This represented a 150 per cent increase on the same day the previous week.
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Two new cases were diagnosed on Sunday and revealed the following day, and since then another two cases - all linked - have been reported.
Testing numbers have steadily declined since last Wednesday, but the impact of the discovery of these new cases remains to be seen.
NSW Health has now deemed Wollongong an area of concern.
"People should be particularly vigilant, and don't hesitate to come forward for testing at the slightest symptom," deputy chief health officer Dr Jeremy McAnulty said.
Almost 16,800 Wollongong residents and more than 6200 Shellharbour residents have been tested for COVID-19 in the past two weeks.
A record 83,477 people across NSW were tested in the 24 hours to 8pm Tuesday - an increase of over 20,000 on the previous day.
In its latest COVID-19 update, NSW Health thanked the community for getting tested.
"High testing numbers are vital in detecting cases of COVID-19 in order to prevent further transmission, and to keep our friends and families safe," it said.
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